The present invention relates to a method and a device for producing a chain which comprises chain links 2 and connecting elements 1, made from formable materials, in particular from plastic.
The invention is preferably used for the substantially continuous production of energy guiding chains, proceeding from at least one injection molded part or extruded part and with the execution of forming and separating operations. The energy guiding chains which are produced in this way comprise a plurality of links having individual connecting elements, the chains comprising elements which are connected to one another and have, at their ends, two pivots which extend to the outside or two connecting openings, the diameter of which corresponds to the diameter of the pivots, adjacent chain links being connected by the pivots which engage into the connecting openings.
Energy guiding chains, also called energy chains or drag chains, are used to convey flexible lines, in particular supply lines, to a movable or displaceable consumer. These energy guiding chains are composed of a multiplicity of chain links which have a box-shaped profile. At their ends, these chain links have an articulated connection, about which they pivot with respect to one another. Limitation of the angle ensures that the lines which are guided in the energy guiding chain are bent only in a defined bending radius.
Various methods for the production of energy guiding chains are known in the prior art. Here, the individual chain links are usually manufactured as injection molded parts from plastic. Subsequently, a predefined number of chain links are connected to one another to achieve the desired length of the energy guiding chain. At one end, the chain links usually have in each case one pivot on opposite sides of the box profile, while two lug-like projections are provided at the other end, which projections have in each case one opening, the diameter of which corresponds to the diameter of the associated pivot. For connection, the two lugs are bent apart from one another. The lugs are pushed over the two pivots, until the pivots latch into the connecting openings.
One disadvantage here is the complicated multiple-stage production and assembly operation.
According to DE 100 17 514 A1, a method for producing guide chains from plastic is known. These guide chains comprise chain links having a box profile, each chain link having a basic body with pivots and connecting openings, adjacent chain links being connected rotatably by engagement of the pivots into the connecting openings. In this method, first of all a box-shaped extruded part is provided, subsequently articulated connections are produced by forming and/or separating operations which in each case form the outer contour of the pivots. The side walls are separated in each case into an inner and outer part; the outer side part walls are severed. The inner side part walls are severed until finally the upper and lower faces of the box profile are likewise severed.
It is a disadvantage that, in these production steps, a multiplicity of individual parts are required for separating operations, for the execution of which complicated knives having delicate blades are required.
Furthermore, it is known in the prior art to construct single-piece energy guiding systems by first of all elongate components being extruded and the latter subsequently being configured in a plurality of processing steps by mechanical processing such as punching, cutting or bending, in such a way that they can be deflected in predefined radii.
It is a disadvantage here that the articulated connections of said guide chains do not exhibit sufficient flexibility by corresponding cross-sectional change in the extruded body and are therefore at risk of fracture.
It is a disadvantage here that these profiles which are produced continuously require great degrees of freedom with subsequently introduced functions and are susceptible to wear.
According to DE-A1 197 10 489, a method for producing a guide chain is known, which guide chain is also denoted there as a protective element for movably laid lines. In order to produce this protective element, first of all a flat plastic part is injection molded or cast in one piece, which plastic part has segments which are connected to one another by bendable bridges. Each protective element can be compared with a chain link and has a base face, two side faces and an upper face, connected to one another by predetermined bending points, in the form of a band. The individual faces can be folded to form a box-shaped segment, the upper face element being connected by way of the free end to the free edge of one side face segment. Whereas the two side face parts are joined to two opposite sides of the base face element, the individual adjacent base face elements are connected to one another at their other longitudinal sides, with the result that, when the respective face parts which are assigned to the respective base faces are folded to form a box-shaped element, the respective box-shaped segments (or chain links) are connected via a predetermined bending point on the longitudinal edges of the base faces.
High assembly expenditure is also required in this method, as the individual segments have to be folded from the face elements. Chains of this type have low stability, as the box-shaped profile ensures only low dimensional stability in the region of the edges, on which the segments are folded. Finally, the predetermined bending points which are produced by the reduction in the material thickness are also subjected to the risk of fracture on account of material fatigue phenomena during the use of the guide chain.
According to DE-A1 197 10 489, the side face segments are to be provided with articulated parts in the form of pivots and guide holes, with the result that the joint parts of respectively adjacent links engage into one another after the folding of individual segment parts.
It is also a disadvantage in this method that complex folding of the individual box-shaped profiles is performed.